Regex Tester
Test regular expressions in real-time - fully client-side
Regex Tester
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What this tool does
Interactive regex tester - type a pattern and see matches highlighted in real time. Supports flags (g, i, m, s, u), displays capture groups, and shows the match count. Fully client-side using the browser's native regex engine.
Who it's for: Developers crafting validation patterns, data analysts building log parsers, and anyone debugging a finicky regex.
When to use
- •Test a regex against sample text before shipping code.
- •Debug why a validation pattern rejects valid input.
- •Extract capture groups from log lines.
- •Experiment with regex flags to see behavior changes.
How it works
- 1Paste test text in the content area.
- 2Type your regex and toggle flags.
- 3Matches are highlighted; capture groups are listed.
- 4Runs entirely in-browser - no data upload.
Tips
- •JavaScript regex lacks some Perl features (possessive quantifiers, conditionals).
- •Use the u flag for proper Unicode matching.
- •Always anchor (^ and $) when validating whole-string input.